The present invention relates generally to combustion chamber liners and more particularly to a method of repairing damaged transpiration cooled liners.
In gas turbine engines, gases are heated by mixing the gases with fuel and burning the mixture. The mixing and burning occurs in an annular combustion chamber formed between an annular inner liner and an annular outer liner. A dome at an upstream end of the combustion chamber has fuel nozzles which deliver fuel to the chamber and mixers which mix the fuel with the flowpath gases. Over time, the high temperatures and corrosive combustion gases damage the liners in the transpiration cooled region.
Early combustion chamber liners were made from sheet metal rings which were brazed together. These liners had recessed cooling holes spaced along the liners for introducing film cooling air to cool the liners. When these liners became damaged, the damaged rings were removed and replaced using a process generally identical to the process used to make the liners originally. More recently, transpiration cooled liners having thousands of small cooling holes have been used. Most of these liners are cast or made from forged rings which are welded together and machined to the final part shape. In the past, these liners have been discarded when they became extensively damaged.
Among the several features of the present invention may be noted the provision of a method of repairing an annular transpiration cooled liner for a combustion chamber of a gas turbine engine. An annular portion of the liner including a damaged region is removed from between an upstream section and a downstream section of the liner. Sheet metal is formed into an annular replacement section having at least one axial seam extending between an upstream end and a downstream end of the replacement section. The replacement section is sized and shaped similarly to the removed annular portion of the liner. The upstream end of the formed annular section is joined to the upstream section of the liner and the downstream end of the formed annular section is joined to the downstream section of the liner.
Other features of the present invention will be in part apparent and in part pointed out hereinafter.